1) Field of the Invention
The present invention relates to a cartridge transferring robot for use in a library apparatus which stores a large number of cartridges such as magnetic tape cartridges and optical disk cartridges, with the cartridge transferring robot conveying the cartridges among a storage unit (or rack), a cartridge entry/exit station and a drive unit within the library apparatus.
2) Description of the Related Art
In general, a library apparatus functions as a large-capacity external storage unit, and a storage unit in its locker stores several thousands of cartridges each accommodating, for example, a magnetic tape as a storage medium. Access such as write/read of recording/recorded data is automatically done toward the storage medium within each of the cartridges.
Furthermore, in addition to the aforesaid storage unit for storing the cartridges, the library apparatus is equipped with a station [for example, a CAS (Cartridge Access Station), a DEE (Direct Entry/Exit), and an FES (Forced Exit Station)] for carrying out the entry of the cartridges from the external environment into the apparatus or vice versa, a plurality of magnetic tape drive units (which will be referred hereinafter to as MTUs) for conducting access such as write/read of recording/recorded data toward a storage medium (magnetic tape) within a cartridge, and a cartridge transferring robot [automatic transferring robot; which will be referred hereinafter to as an accessor (ACC)] for performing the conveyance among the storage unit, the cartridge entry/exit station and the MTU.
In the case of such a library apparatus, on receiving an access demand to one cartridge from a host unit or the like, the accessor moves to the storage unit to search the directing cartridge and then transfers that cartridge up to the MTU in a state of gripping or holding it through the use of a hand mechanism, thereby putting it in the MTU. Whereupon, the MTU processes the storage medium (magnetic tape) within the cartridge. The cartridge discharged from the MTU after the completion of the processing is regripped by the hand mechanism of the accessor and transferred up to the storage unit by that accessor to be stored in a given location.
In general, only one type of the cartridges is transferred by the accessor, and the library apparatus performs large-capacity backup of data through the use of that one type of cartridge (media). Accordingly, the accessor is naturally taken to have a function of transferring only one type of cartridge.
On the other hand, since the library apparatus is for backing up a large quantity of data, the users may desire to retain data through the use of two or more types of media but not one type of media. However, because as mentioned above the prior library apparatus is designed to handle only one type of media, this apparatus is incapable of meeting such requirements.
Furthermore, the difference between the types of media naturally causes the difference between the sizes (external dimensions or configurations) of the media, and hence, for certain insertion of the media with different sizes into storage units or MTUs, the accessor is required to always reset various types of media at a reference position. For this reason, difficulty is encountered to surely insert the various types of media into the storage units or MTUs corresponding to those types only in a manner that the accessor (automatic transferring robot) are designed to cope with transferring two or more types of media.